MAKE THEM HARD TO GUESS. The most common passwords are “password” and “123456.” Hackers try easily-guessed passwords because they’re used by half of all people. A strong password has seven or more characters and a combination of upper and lower case letters, numbers, and symbols (like !@#$&*). A phrase can also be a strong password (and may be easier to remember), like “B1gMac&frieS.”